I don't think the problem with IE was necessarily consolidation as much as letting Microsoft be the only ones with the ability to modify or extend the engine. In my mind there would be nothing wrong with Mozilla joining Microsoft in basing their browser on Blink+V8. In fact it might even be a better way to ensure Google can't steer Chrome the same way Microsoft did since no matter how great they make it the competition will always be dragged along with it, there to become the better drop in option should Google decide to stop leading the push.